Novel coronavirus (COVID-19) a World Pandemic where we are now.

SIR model

I have been following with a bit of apprehension the COVID-19 pandemic evolution around the world, from Asia to pretty much all over the world. Human kind has lived and until now survived many epidemics and pandemics, but this virus seems to have taken everyone by surprise, where even many important nation representatives showed no interest in dealing with the pandemic calling it, a simple flue virus.

The pandemic, initiated in China Hubei Province in Wuhan. After a slow start by the Chinese governement to grasp the scale of the epidemic (at that time) it took tough measures, really going to extremes to contain the virus. It seems that their effort showed results and at this point China controlled the Pandemic in their territory but unfortunately has not solved the problem. Although the number of cases have reduced to zero, or almost there, it is sustained at high control and pressure measures. I can’t see any tourist wait 14 days quarantine to discover China, maybe only a few could afford it. Markets, shops, transportations services that serve millions will have to be limited.

Asian countries took the Pandemic seriously and prepared for the worst, closing borders, testing, isolating contaminated people and preventively reducing human circulation.

Europe on the other hand seems to be the new Pandemic center and Italy, it’s most affected country, having high number of deaths and many new infected cases every day. Throughout all Europe the pandemic seems to be growing without stop. It seems Europe took more time to implement hard measures and seems to be on the defensive side to reduce the number of new cases to avoid overcrowding their health care systems.

In the USA after a dangerous denial period the disease seems to be taking over and forcing many states to take hard measures, which in turn forced their president to declare national emergency. Interesting the UK and Brasil followed the American denial, however the growing numbers of infected people and deaths slowly but surely is changing state representatives opinion, that in turn make their presidents change stance.

In Africa we are starting to see a slow rise in cases, however numbers are expected to explode, in the comming weeks/days, for they do not have the capability that most developed countries have to deal with this pandemic.

This Pandemic, like any other can be dealt with  mitigation actions like prophylactic containment and/or by suppression actions, which mainly consists of mass individual testing. The Asian countries and the Western countries are using different tactics to deal with the Pandemic. Asian countries use extreme mitigation  actions combined with suppression actions which until now have proven to be effective. Interestingly the Western countries seem to be on the defensive side with mostly mitigation actions, with however not so effective results. A good explanation about this can be seen in the following link: https://www.theatlantic.com/ideas/archive/2020/03/how-we-beat-coronavirus/608389/

Interestingly Italy tried with very good results the usage of suppression actions on the pandemic but on a small scale. The difficulty to implement these actions on large cities with generalised infections is that it requires a great deal of resources and organisation. A good report on this subject can be seen here: https://www.ft.com/content/0dba7ea8-6713-11ea-800d-da70cff6e4d3

Certainly East and West have used models to predict the pandemic evolution, scientists, politics and the general community certainly got shocked when they noticed that doing nothing could yield total chaos. Models predict an insane amount of infected people at the peek of the pandemic. 

Models help us understand and predict the behaviour of Pandemics. A good reference  to understand what models exist and their boundary conditions can be seen in this article: https://chengjunwang.com/post/en/2013-03-14-learn-basic-epidemic-models-with-python/ 

The SIR model (S – Susceptible, I – Infected, R- Recovered) can help us understand the severity of our current world situation. For example for a 1 million population, 14 day mean recovery (time during which an infected individual can pass it on) and 0.2 value factor that compensates the rate at which an individual can come in contact with others, gives us a good prediction of what to expected of any epidemic response.

In this demonstration example case, almost all of the population gets infected and we get an infection peek of more than 20% of the population. No health care system can deal with such a wave. 

I will end this post with a few questions that are in my mind so far:

    • Will the Western approach of low suppression (reactive to symptomatic patients) and high mitigation be enough?
    • Are the models used by scientists taking into account the fact that infected people don’t know they are infected and don’t present symptoms?
    • Even if we control the outbreak, how will the economy survive if most of us fear a second wave due to lack of immunity towards the virus?
    • How long can the world live in social containment?
SIR model
Pandemic SIR model (see https://scipython.com/book/chapter-8-scipy/additional-examples/the-sir-epidemic-model/